RP 2-14

Study of heart disease in the Adult Health Study population using echocardiography


There is much evidence that exposure to high-dose medical irradiation increases risk of cardiovascular disease (CVD). Recent Life Span Study (LSS) reports demonstrated an excess risk of mortality from CVD, especially hypertensive heart disease, heart failure, and rheumatic heart disease after whole-body exposure to atomic-bomb radiation. Other epidemiologic studies have indicated that medical radiation is associated with dose-dependent perfusion defect in patients treated for breast cancer with radiation therapy, which may be a cause of heart damage. Past experimental findings reported that total body irradiation in rats was associated with development of diastolic dysfunction. We therefore hypothesized that atomic-bomb radiation may cause diastolic dysfunction among the survivors. Based on echocardiograph assessment and blood markers in the Adult Health Study (AHS) subjects who were 15 years of age or younger at the time of bombings, we will diagnose heart failure and categorize it into its subtypes. Our main purpose is evaluating radiation effects on diastolic heart failure, one subtype of heart failure. However, we will also examine as secondary endpoints systolic heart failure, and hypertensive, valvular, and ischemic heart disease. This research protocol plans to conduct echocardiography with standard techniques to collect a broad range of information on the above cardiac diseases. Once the images obtained by the standard echocardiograms are stored in an appropriate format, we will be able to conduct more advanced speckle tracking analysis. We will plan a separate research protocol regarding this speckle tracking analysis.

Relevant measures for all these types of CVD will be available from the echocardiograms, conforming to the guidelines and recommendations from the American Society of Echocardiography (ASE). The expected number of subjects for the study is about 2,700 AHS members (including in utero survivors) in Hiroshima and Nagasaki who were ?15 years old at the time of bombing. We will also measure biomarkers that play an important role in the development of cardiac dysfunction and fibrosis, as well as remodeling that arises from radiation-related damage-repairing processes in cardiac tissues.